The overall goal is to understand the molecular events involved in the regulated expression of the pituitary glycoprotein hormone genes, luteinizing hormone (LH), follicle stimulating hormone (FSH) and thyroid stimulating hormone (TSH). These hormones are dimers, each containing a common alpha-subunit and different beta-subunit which confers the biological specificity. The studies seek to examine the mechanisms which are responsible for hormonal regulation of glycoprotein hormone subunit genes and the mechanisms which may permit coordinate regulation of alpha- and beta-subunit genes. Attention will be focused on identification of the cis-acting DNA sequences and trans-acting factors which are necessary for appropriate expression of glycoprotein hormone subunit genes. The specific aims include: 1) The DNA sequences which are required for basal, tissue-specific expression as well as the DNA sequences which mediate hormonal regulation of glycoprotein hormone subunit gene expression will be identified by deletion and clustered point mutation studies. The effects of DNA deletions or mutations will be assessed by gene transfer studies using primary cultures of rat pituitary cells and fusion genes containing the putative regulatory regions and promotor of glycoprotein hormone genes linked to a firefly luciferase marker gen. The initial studies will focus on the cis-acting DNA sequences of the LH- beta and FSH-beta genes. 2) Trans-acting factors which may be responsible for basal or hormonal regulation of glycoprotein hormone gene transcription will be identified by gel mobility shift assays using DNA fragments shown to be important as assessed by the deletion/mutation/gene transfer studies. 3) An effort will be made to identify trans-acting factors which may be involved in the coordinate regulation of alpha-and beta-subunit gene expression. 4) DNA binding proteins which interact with specific glycoprotein hormone gene sequences will be purified by conventional and affinity chromatography techniques and cloned cDNAs isolated. These studies would provide increased understanding of the specific mechanisms involved in the hormonal regulation of the transcription of these physiologically important genes.